Firing on the spot is only legal in exceptional circumstances, e.g. when they can prove you simply didnt work your hours, or something (outside of paid and u paid leave, paid and unpaid sick leave).
We also get maternal and paternal leave which is very nice.
Overtime, health insurance, etc. are also dictated to some degree by law in a lot of countries.
The fact that you (Americans) feel enslaved is because you choose to elect a government that doesn't care about any of that.